Today, most luggage cases over a certain size include wheels to ease their transport. One problem encountered is how to mount these wheels firmly and dependably to the luggage case. This mounting problem is especially compounded when the wheel is of the type cantilevered from one end of an axle fixed to the case. That is, a cantilever wheel is mounted by its axle to a luggage case on only one side of the rotating tire. This is in contrast to a wheel mounted on an axle supported by the luggage case on both sides of the rotating wheel. A cantilever-type wheel is desired where the wheel base of the luggage case (that is the distance between a pair of wheels) must be maximized. An example would be the type of case called an upright case, especially where this upright case is used to carry other luggage cases such as that shown in U.S. Pat. No. 4,759,531 specifically incorporated herein by reference. This patent is assigned to Samsonite Corporation, assignee of the subject invention.
Not only is it desirable that the wheel base be on a luggage case as large as possible, limited only by the width of the wheeled luggage case, but the mounting assembly for the wheel must be extremely robust. Weight of the case on the wheels is a prime factor, but since the case is specifically designed to carry other cases, weight carried by just two wheels can be considerable.
The dynamic stresses to which such a wheel system is subjected also can be enormous, especially if the luggage to which the assembly is to be attached is of a type molded of one monolithic piece. Such luggage cases consist of two molded shells. Attaching such a robust wheel system to a luggage shell may result in stress cracking the molded shell because the load borne by the wheels, and thus the stress caused by that load, tends concentrate in a relatively small portion of the shell structure. This is especially true in the absence of a true undercarriage mechanism, such as that disclosed in the above-referred to patent. Such an undercarriage is expensive, complicated to assemble, and adds considerably to the weight of the luggage case.